Figure 3: Chemogenetic activation of GLP-1 neurons mice decreases nicotine intake.

(a) Representation of NTS and the site of stereotaxic DREADD virus injections in Phox2b-Cre of Gcg-Cre mice. (b) Top: DIO vector design and selective expression in Phox2b-Cre neurons. Bottom: representative micrograph showing selective expression of AAV-DIO-hM3Dq-mCitrine vector in GLP-1-immunopositive neurons in Phox2b-Cre mice. Scale bar, 50 μm. (c) Non-DIO vector design (top) and representative micrograph showing nonspecific expression throughout cNTS neurons in Phox2b-Cre mice (bottom). Scale bar, 50 μm. (d) Mean (± s.e.m.) number of nicotine infusions after saline or CNO (1 mg/kg, intraperitoneally) injection in Phox2b-Cre mice expressing DIO-hM3Dq. ***P = 0.0032, paired t-test; n = 6. (e) Mean (± s.e.m.) number of nicotine infusions after saline or CNO injection to Phox2b-Cre mice expressing hM3Dq (n = 5). P = 0.0660, paired t-test. (f) Mean (± s.e.m.) number of nicotine infusions after saline or CNO injection in Phox2b-Cre mice expressing AAV-EGFP vector (n = 5). P = 0.2643, paired t-test. (g) Top: DIO vector design. Bottom: representative micrograph showing selective expression of AAV-DIO-hM3Dq-mCherry in GLP-1-immunopositive neurons of Gcg-Cre mice. Scale bar, 20 μm. (h) Mean (± s.e.m.) number of nicotine infusions after saline or CNO (3 mg/kg, intraperitoneally) injection in Gcg-Cre mice expressing FLEX-hM3Dq. *P = 0.0011, paired t-test; n = 8.